按钮后面的LinearLayout上的OnTouchListener

Question

I am working on an Android application using C# in Xamarin. In my axml file, I have a LinearLayout with a certain ID that I have assigned a onTouchListener to. The problem is that as long as the buttons I have in my design are on top of the linearLayout, the onTouchListener is never triggered. If I set one of the buttons to invisible, then it works.

Is it possible to still have the onTouchListener react even though there are Controls in the way?

This is my axml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/LinearLayout1"
    android:layout_height="fill_parent"
    android:layout_width="fill_parent"
    android:orientation="vertical">
    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:orientation="horizontal"
        android:layout_weight="1">
        <Button
            android:id="@+id/button1"
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="1"
            android:layout_marginBottom="0.0dp"
            android:background="@android:color/holo_green_light"
            android:soundEffectsEnabled="false" />
        <Button
            android:id="@+id/button2"
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="2"
            android:background="@android:color/holo_blue_light" />
    </LinearLayout>
    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:layout_weight="1">
        <Button
            android:id="@+id/button3"
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="3"
            android:background="@android:color/holo_red_light" />
        <Button
            android:id="@+id/button4"
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="4"
            android:background="@android:color/holo_orange_light" />
    </LinearLayout>
</LinearLayout>

This is how I set the onTouchlistener for the linearLayout:

LinearLayout linLay = FindViewById<LinearLayout>(Resource.Id.LinearLayout1);
linLay.SetOnTouchListener(new MyTouchListener(this));

This is a custom touch listener class:

    public class MyTouchListener : Java.Lang.Object, View.IOnTouchListener
    {
    Context activityContext;

    public MyTouchListener(Context ac)
    {
        activityContext = ac;
    }

    public bool OnTouch(View v, MotionEvent e)
    {
        float x = 0.0f;
        float y = 0.0f;

        if (e.Action == MotionEventActions.Down)
        {
            // do stuff

            x = e.GetX();
            y = e.GetY();

            Toast.MakeText(activityContext, x.ToString(), ToastLength.Short).Show();


            return true;
        }
        //if (e.Action == MotionEventActions.Up)
        //{
        //    // do other stuff
        //    return true;
        //}
        return true;
    }
}

And finally, this is how I set up the button click listener:

        Button button = FindViewById<Button>(Resource.Id.button1);
        button.Click += (s,e) =>
        {
            //int i = count % s.Count;
            //if(i > 28)
            //    Toast.MakeText(this, button.GetX().ToString(), ToastLength.Short).Show();

            button.Text = string.Format("{0}", count++);

        };

Answer 1

You have to intercept the touch event. In order to do that you have to subclass LinearLayout and override onInterceptTouchEvent() :

public class MyLinearLayout extends LinearLayout {
    public MyLinearLayout(Context context) {
        super(context);
    }

    public MyLinearLayout(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public MyLinearLayout(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        Toast.makeText(getContext(), "onTouch", Toast.LENGTH_SHORT).show();
        return true;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return true;
    }
}

Your xml :

<?xml version="1.0" encoding="utf-8"?>
<com.your.package.MyLinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:id="@+id/LinearLayout1"
              android:layout_height="fill_parent"
              android:layout_width="fill_parent"
              android:orientation="vertical">
    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:orientation="horizontal"
        android:layout_weight="1">
        <Button
            android:id="@+id/button1"
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="1"
            android:layout_marginBottom="0.0dp"
            android:background="@android:color/holo_green_light"
            android:soundEffectsEnabled="false" />
        <Button
            android:id="@+id/button2"
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="2"
            android:visibility="invisible"
            android:background="@android:color/holo_blue_light" />
    </LinearLayout>
    <LinearLayout
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:layout_weight="1">
        <Button
            android:id="@+id/button3"
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="3"
            android:background="@android:color/holo_red_light" />
        <Button
            android:id="@+id/button4"
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="4"
            android:background="@android:color/holo_orange_light" />
    </LinearLayout>
</com.your.package.MyLinearLayout>

Now any touch event on the layout will be handled by your custom MyLinearLayout .

Answer 2

You need to extend (inherent) the parent linear layout so that you can intercept touch events from the nested children layouts. Override these two methods to receive touches from the children. Then in your xml you will add "myCustomLinearLayout" or whatever you name the your custom linear layout class. It should be pretty similar in C# / Xamarin.

@Override
   public boolean onInterceptTouchEvent(MotionEvent ev) {
     return true; // With this i tell my layout to consume all the touch events from its childs
  }

@Override
public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
    // Log.d(TAG, String.format("ACTION_DOWN | x:%s y:%s", 
        break;
    case MotionEvent.ACTION_MOVE:
    //Log.d(TAG, String.format("ACTION_MOVE | x:%s y:%s", 
        break;
    case MotionEvent.ACTION_UP:
        break;
    }
    return true;
}